.\" Copyright (c) 1995
.\"	Bill Paul <wpaul@ctr.columbia.edu>.  All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    documentation and/or other materials provided with the distribution.
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.\"    must display the following acknowledgement:
.\"	This product includes software developed by Bill Paul.
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.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
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.Dd February 5, 1995
.Dt YPXFR 8
.Os
.Sh NAME
.Nm ypxfr
.Nd "transfer NIS database from remote server to local host"
.Sh SYNOPSIS
.Nm /usr/libexec/ypxfr
.Op Fl f
.Op Fl c
.Op Fl d Ar target domain
.Op Fl h Ar source host
.Op Fl s Ar source domain
.Op Fl p Ar path
.Op Fl C Ar taskid program-number ipaddr port
.Ar mapname
.Sh DESCRIPTION
The
.Nm
utility copies an
.Tn NIS
database (or
.Pa map )
from one
.Tn NIS
server to another using
.Tn NIS
services.
In
.Fx ,
.Nm
is generally invoked by
.Xr ypserv 8
when it receives a map transfer request from
.Xr yppush 8 .
The
.Nm
utility is used primarily in environments where several
.Tn NIS
servers are in use in a single domain.
One server, the
.Tn NIS
master, maintains
the canonical copies of all
.Tn NIS
maps, and all the other servers,
the
.Tn NIS
slaves, copy new versions of the maps from the master whenever
any updates are made (i.e., when a user updates their password via
.Xr yppasswd 1 ) .
.Pp
When run,
.Nm
creates a temporary database file in
.Pa /var/yp/[domainname] ,
and fills it with the contents of
.Ar mapname
as supplied by the specified
.Ar source host .
When the entire map has been transferred,
.Nm
deletes the original copy of
.Ar mapname
and moves the temporary copy into its place.
When the transfer is
complete,
.Nm
will attempt to send a 'clear current map' request to the local
.Xr ypserv 8
process to clear any possible references it may still have to the
stale map.
.Pp
Note that all files created by
.Nm
are owner readable and writable only for security reasons.
Since the
.Tn NIS
maps and the directory in which they reside are normally owned by
root, this prevents non-privileged users from making unauthorized
modifications.
.Pp
In order to maintain consistency across all
.Tn NIS
servers,
.Nm
can be run periodically in a
.Xr cron 8
job.
Maps which change infrequently
need only be updated once a day (preferably late at night when system
usage is lowest), whereas those that are subject to frequent changes
(such a
.Pa passwd.byname
and
.Pa passwd.byuid )
should be updated perhaps once every hour.
Using
.Xr cron 8
to automatically
update the
.Tn NIS
maps is not strictly mandatory since all updates should
be propagated by
.Xr yppush 8
when
.Pa /var/yp/Makefile
is run on the
.Tn NIS
master server, however it is good practice
on large networks where possible outages could cause
.Tn NIS
servers to fall out of sync with each other.
.Pp
When
.Nm
is invoked without a controlling terminal, e.g.\& from inside
.Xr ypserv 8 ,
it logs all its output using the
.Xr syslog 3
facility.
.Sh NOTES
The
.Fx
version of
.Nm
has support for a special map transfer protocol which works in
conjunction with the
.Fx
.Xr rpc.ypxfrd 8
server.
This protocol allows it to transfer raw map database files from
the
.Tn NIS
master server and can be many times faster than the standard
transfer method, particularly for very large
.Tn NIS
maps.
The
.Nm
utility will check to see if the
.Xr rpc.ypxfrd 8
server is registered on the
.Tn NIS
master server and attempt to use
it if it is present.
If it is not it will fall back to the standard
transfer method, copying the map contents from
.Xr ypserv 8
and creating new maps instead.
.Pp
Note that while the
.Fx
ypxfrd protocol is conceptually similar
to the SunOS ypxfrd protocol,
the
.Fx
protocol is not compatible with
Sun's, therefore it will not work with Sun's ypxfrd server.
.Fx
slave systems can still transfer maps from any
.No non- Ns Fx
.Tn NIS
server,
however they will only be able to take advantage of the faster protocol
if the master server is also running
.Fx .
.Sh OPTIONS
The following options and flags are supported by
.Nm :
.Bl -tag -width indent
.It Fl f
Force a map transfer.
Normally,
.Nm
will not transfer a map if it determines that the
.Tn NIS
master's copy
is not newer than the existing copy already on the local host: the
.Fl f
flag forces a transfer regardless of which server's version is more recent.
.It Fl c
Do not send a 'clear current map' request to the
.Xr ypserv 8
process running on the local host.
This flag is normally used when
invoking
.Nm
manually on a machine that is not yet running
.Xr ypserv 8 .
Without this flag, failure to contact the local
.Tn NIS
server will cause
.Nm
to abort the transfer.
.It Fl d Ar target domain
Specify a target domain other than the current
.Tn NIS
domain.
.It Fl h Ar source host
Specify the name of the host from which to copy the
.Tn NIS
maps.
This option
is used to ensure that
.Nm
only copies maps from the
.Tn NIS
master server.
.It Fl s Ar source domain
Specify the domain from which to transfer a map, in the event that
the transfer is being done across two different
.Tn NIS
domains.
.It Fl p Ar path
Specify the top level directory containing the
.Tn NIS
maps.
By
default, this path is
.Pa /var/yp .
The
.Fl p
flag allows you to specify an alternate path should you wish to
store your
.Tn NIS
maps in a different part of the file system.
The
.Tn NIS
server,
.Xr ypserv 8 ,
passes this flag to
.Nm
if it too has been told to use an alternate path.
.It Fl C Ar taskid program-number ipaddr port
These options are used only when
.Nm
is invoked by
.Xr ypserv 8
in response to a map transfer request initiated by
.Xr yppush 8 .
In this instance,
.Nm
needs to 'callback' to the
.Xr yppush 8
process and interact with it, so
.Xr yppush 8
passes to it an IP address
.Ar ipaddr ,
port number
.Ar port ,
registered program number
.Ar program-number
and a transaction ID
.Ar taskid
that it can use to contact the waiting
.Xr yppush 8
process on the master server.
.It Ar mapname
The name of the map to transfer.
.El
.Sh FILES
.Bl -tag -width Pa -compact
.It Pa /var/yp/[domainname]/[maps]
The
.Tn NIS
maps for a particular
.Tn NIS
domain.
.El
.Sh SEE ALSO
.Xr yp 8 ,
.Xr yppush 8 ,
.Xr ypserv 8
.Sh AUTHORS
.An Bill Paul Aq Mt wpaul@ctr.columbia.edu
